The present invention generally relates to erosion resistant gas turbine engine compressor components having a diamond-like coating (DLC) thereon, and to methods for forming such compressor components.
In the compressor of gas turbine engines, axial flow compressor blades and stator vanes may be exposed to sand, dust, and other air-borne particulates for extended periods of time. Ingestion of particulates, such as sand, by gas turbine engines may lead to component failure, and drastically accelerates deterioration in engine performance. Some gas turbine engines in rotary wing aircraft that routinely demonstrate adequate operational performance for 1500 hours in a clean environment, may demonstrate adequate operational performance for as little as 100 hours in severe environments such as deserts. This deterioration in engine performance is due principally to loss of compressor efficiency caused by erosion of compressor blades. Thus, erosion of compressor blades due to ingestion of sand or other particulates leads to decreased life cycle of turbine engines (i.e., their premature removal), or necessitates compressor blade replacement.
Prior art gas turbine engine components, including compressor blades, have been coated with aluminides to inhibit oxidation and corrosion of the component surface. However, such coatings do not prevent erosion of compressor blades by sand or other particulates ingested by the engine.
Compressor blades have been coated with titanium nitride (TiN) for erosion protection. However, such TiN coatings are relatively thick, for example, up to about 20 microns or more, and cracks formed within such coatings tend to propagate to the parent material, i.e., compressor blade, thereby decreasing fatigue life of the compressor blade.
U.S. Pat. No. 5,423,475 to Burke et al. discloses a diamond film applied to an aluminum or aluminum alloy substrate by first depositing the diamond film on a silicon substrate, chemically etching with hydrofluoric acid to remove most of the silicon to form a hybrid diamond/silicon layer, and bonding the hybrid diamond/silicon layer to the aluminum or aluminum alloy substrate.
U.S. Pat. No. 6,099,976 to Lemelson et al. discloses a multilayer coating for gas turbine engine parts that have a thermal barrier coating (TBC) thereon to protect the parts from elevated temperatures, wherein a diamond film overlay is applied to a ceramic, columnar TBC to improve erosion resistance of the TBC.
U.S. Pat. No. 5,728,465 to Dorfman et al. discloses a corrosion resistant coating comprising a diamond like solid state material which comprises a diamond-like network stabilized with hydrogen, a silicon network stabilized with oxygen, and optionally various dopant elements or dopant compounds.
The presence of hydrogen, or other elements (other than carbon), in a DLC may materially interfere with the interlocking sp3 network of covalent bonds thereby materially weakening structural rigidity.
As can be seen, there is a need for a gas turbine engine having DLC-coated compressor components, such as axial flow compressor blades and stator vanes, for erosion protection of the compressor components, for maintaining engine performance during operation in the presence of air-borne particulates, and for maximizing the life cycle of the compressor components.
There is a further need for a simple, rapid, and straightforward process for forming a DLC directly on an airfoil substrate surface, such as a surface of an axial flow compressor blade. There is a further need for a method for making a compressor component for a gas turbine engine, such as an axial flow compressor blade or a stator vane, wherein the compressor component is coated with a DLC in a hydrogen-free deposition process, whereby the adverse effects of hydrogen contamination of the DLC are avoided.